This invention relates to apparatus for use in the fabrication of semiconductor devices and more particularly to carriers for wafers or other substrates for use in production of integrated circuits.
A wafer is typically a substantially cylindrical piece of silicon, the height of which is very small in proportion to its diameter. Such a wafer normally goes through a large number of processing steps until a number of integrated circuits have been fabricated on the wafer. These processing steps require handling of the wafer by a number of different machines.
In the manufacture of various types of integrated circuits, it is at times desirable to use more than one size of wafer. Six inch diameter and four inch diameter wafers are among those most commonly used, although a variety of sizes are possible. In order to change from one size to another, the equipment for handling the wafers must be adjusted or retooled. Such adjustment or retooling results in expense as well as periods of time when the equipment is out of use. Clips can be provided on processing equipment to secure wafers. However, such clips cover a fairly large area of the top surface of the wafer. Imperfections or particles on the clips can cause scratches on the wafer.
Alternatively, separate processing facilities must be provided for different sizes of wafers. This alternative is also expensive.
Objects and advantages of this invention will be evident from the detailed description of a preferred embodiment which follows.